From 9d28c3ec90b257a93d184a1aef3cbbde9cbaa19c Mon Sep 17 00:00:00 2001
From: Jeff Smale <6363749+jeffsmale90@users.noreply.github.com>
Date: Mon, 4 Apr 2022 20:25:48 +1200
Subject: [PATCH] perf: improve performance of the persistent cache used in
 forking

- Make 'lt' argument more specific in order to retrieve less entries
- Convert block hash to Buffer type immediately on initiatisation (rather than every time we get / put an entry)
---
 .../forking/persistent-cache/persistent-cache.ts  | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/src/chains/ethereum/ethereum/src/forking/persistent-cache/persistent-cache.ts b/src/chains/ethereum/ethereum/src/forking/persistent-cache/persistent-cache.ts
index 654d0b6440..7ec06cb6be 100644
--- a/src/chains/ethereum/ethereum/src/forking/persistent-cache/persistent-cache.ts
+++ b/src/chains/ethereum/ethereum/src/forking/persistent-cache/persistent-cache.ts
@@ -43,7 +43,7 @@ export class PersistentCache {
     AbstractIterator<Buffer, Buffer>
   >;
   protected ancestry: Ancestry;
-  protected hash: Data;
+  protected hashBuffer: Buffer;
   protected request: Request;
   constructor() {}
 
@@ -131,7 +131,7 @@ export class PersistentCache {
   }
 
   async initialize(height: Quantity, hash: Data, request: Request) {
-    this.hash = hash;
+    this.hashBuffer = hash.toBuffer();
     this.request = request;
 
     const {
@@ -325,22 +325,21 @@ export class PersistentCache {
     const height = Quantity.from(blockNumber);
     const bufKey = Buffer.from(key);
     const start = lexico.encode([height.toBuffer(), bufKey]);
-    const end = lexico.encode([
-      Quantity.from(height.toBigInt() + 1n).toBuffer()
-    ]);
+    const end = Buffer.concat([start, Buffer.from([0xff])]);
+
     const readStream = this.cacheDb.createReadStream({
       gt: start,
       lt: end,
       keys: true,
       values: true
     });
-    const hashBuf = this.hash.toBuffer();
+
     for await (const data of readStream) {
       const { key: k, value } = (data as any) as { key: Buffer; value: Buffer };
       const [_height, _key, blockHash] = lexico.decode(k);
       // if our key no longer matches make sure we don't keep searching
       if (!_key.equals(bufKey)) return;
-      if (hashBuf.equals(blockHash) || (await this.ancestry.has(blockHash))) {
+      if (this.hashBuffer.equals(blockHash) || (await this.ancestry.has(blockHash))) {
         return value;
       }
     }
@@ -354,7 +353,7 @@ export class PersistentCache {
     const dbKey = lexico.encode([
       height.toBuffer(),
       Buffer.from(key),
-      this.hash.toBuffer()
+      this.hashBuffer
     ]);
     await this.cacheDb.put(dbKey, value);
     return true;